This section is intended to provide a background to the various embodiments of the technology described in this disclosure. The description in this section may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and/or claims of this disclosure and is not admitted to be prior art by the mere inclusion in this section.
In a Long Term Evolution (LTE) system, System Information (SI) is important as it can provide necessary information to a UE for linking with network. SI is separated into several blocks, including Master Information Block (MIB) and SIBs. Not like MIB being broadcasted in Physical Broadcast CHannel (PBCH), SIBs are all broadcasted in Physical Downlink Shared CHannel (PDSCH). Among these SIBs, SIB1 includes scheduling information of the other SIBs, so SIB1 reception is very important for the UE.
To be specific, SIB1 includes information as follows:                Information about whether a terminal is allowed to camp on the serving cell;        Information about Time Division Duplexing (TDD) configurations;        Scheduling information of the remaining SIBs; and        Value tag to indicate a change has occurred in a SI message.        
As specified in the 3rd Generation Partnership Project (3GPP) specification, SIB1 is typically broadcasted in subframe 5 of the even numbered radio frames. SIB1 needs to be decoded, e.g.,                when UE finishes cell selection or cell reselection;        when UE finishes cell handover;        when UE returns from out of coverage area;        when SI is changed;        upon receipt of Received Earthquake and Tsunami Warning System (ETWS) or Commercial Mobile Alert System (CMAS) indicators; or        if there is no validated update for 3 hours.        
With the communication development, the network deployment is more complex and the intra-frequency interference issue becomes more outstanding. In the intra-frequency interference condition, there are some issues for SIB1 reception in the above scenarios. For a typical serving and neighboring cells deployment, in case of system frame number (SFN) alignment between the two cells, there may be collision of the SIB1 transmission of serving and neighboring cells. When the neighboring cell is strong, UE may not receive SIB1 of serving cell correctly due to interference from SIB1 of neighboring cell, and then the linking procedure between UE and network would be blocked.
FIG. 1 illustrates some examples for describing a SIB1 reception issue in an intra-frequency interference condition. As shown in FIG. 1, Evolved Node B 1 (eNB1) and eNB2 are two neighboring cells and they have an overlay area at cell edge zone. In the overlay area, signals of the two cells are both strong. UE1, UE2 and UE3 are three different users under different conditions.
In a first example, UE1 is to move from eNB1 into eNB2. Because eNB1 is still strong in the cell edge of eNB2, it is not easy to decode SIB1 of eNB2.
In a second example, UE2 is located in the cell edge of eNB2. When UE2 decodes SIB1 of eNB2, it cannot decode SIB1 of eNB2 accurately because of the strong interference from eNB1.
In the third example, UE3 is to move from out of coverage area into the overlay area. In this example, UE3 needs to detect SIB1 of eNB1 or eNB2 depending on cell search and measurement results. Because the two eNBs are both strong, UE3 cannot decode SIB1 of one cell accurately due to the strong interference from the other eNB.
To improve SIB1 reception performance in the intra-frequency interference condition, some traditional solutions have been tried, e.g., use of Cell-specific Reference Signal (CRS) interference cancellation (IC) or Interference Rejection Combining (IRC).
However, CRS IC cannot work well because the SIB1 interference comes from not only the CRS of neighboring cells, but also the SIB1 Resource Elements (REs) of neighboring cells. When the neighboring cells may be much stronger than the serving cell, IRC cannot solve the issue because IRC cannot provide enough performance improvement.
Consequently, neither of the above solutions can solve the SIB1 reception issue. So, there is a need for a solution to enhance SIB1 reception in the intra-frequency interference condition.